Update to null safety

pubspec.yaml

@@ -1,31 +1,31 @@
 name: jisho_study_tool
-description: A new Flutter project.
+description: A dictionary app for studying japanese
 version: 1.0.0+1
 
 environment:
-  sdk: ">=2.1.0 <3.0.0"
+  sdk: ">=2.12.0 <3.0.0"
 
 dependencies:
+  animated_size_and_fade: ^2.0.0
+  division: ^0.9.0
   flutter:
     sdk: flutter
-
-  shared_preferences: "^2.0.3"
+  flutter_bloc: ^7.0.1
+  flutter_slidable: ^0.6.0
+  mdi: ^5.0.0-nullsafety.0
   objectbox: ^1.1.1
-  objectbox_flutter_libs: any
+  objectbox_flutter_libs: ^1.1.1
   path_provider: ^2.0.2
+  shared_preferences: ^2.0.6
+  unofficial_jisho_api: ^2.0.2
+  url_launcher: ^6.0.9
 
-  # cupertino_icons: ^0.1.2
-  mdi: ^4.0.0
-  unofficial_jisho_api: ^1.1.0
-  flutter_bloc: ^7.0.0
-  url_launcher: ^6.0.3
-  division: ^0.8.8
 
 dev_dependencies:
+  build_runner: ^2.0.6
   flutter_test:
     sdk: flutter
-  build_runner: ^1.0.0
-  objectbox_generator: any
+  objectbox_generator: ^1.1.1
 
 flutter:
   uses-material-design: true